The FBI has dug up thousands of pages of classified documents authorities say were buried by Brian Regan (search), a former Air Force master sergeant serving a life sentence for attempting to sell U.S. secrets to Saddam Hussein (search) and others.

The roughly 10,000 pages of documents, as well as videotapes and CD-ROMs, were taken by Regan while he worked at the National Reconnaissance Office (search), which operates the nation's spy satellites. They were buried at undisclosed locations in the Washington area, officials said.

Three federal officials, speaking Monday on condition of anonymity, said authorities believe Regan was hoarding the documents and other materials with plans to sell them to Iraq and three other unidentified countries described as hostile to the United States.

The materials provided details about spy satellites and U.S. early warning systems, among other things, officials said.

Existence of such a large cache of sensitive material, which was only hinted at during Regan's trial earlier this year, helps explain why federal prosecutors initially sought the death penalty in the case and eventually settled on a plea agreement for life without parole.

Some legal experts were surprised at the aggressive stance the government took against Regan, particularly since the CIA's Aldrich Ames and the FBI's Robert Hanssen both had gotten life sentences in what appeared to be far more serious espionage cases.

Regan's defense attorney, Nina Ginsberg, declined comment because of the classified nature of the materials.

Regan, a married father of four from Bowie, Md., was convicted in February of two counts of attempted espionage and one count of gathering national defense information. Prosecutors said Regan was in debt and sought millions of dollars for the information.

Defense lawyers had argued that Regan's attempts to sell secrets to Iraq and China were unsuccessful and that he was engaged more in fantasy than in real espionage.

Regan worked at the National Reconnaissance Office during his time in the Air Force and later worked for defense contractor TRW.

The locations of the buried materials were discovered last fall by guards at the jail in Alexandria, Va., where Regan was being held. They found a map in Regan's cell with specific sites marked, which came after they had earlier confronted Regan about papers he possessed that appeared to be written in code -- papers he quickly flushed down the jail toilet.

Court filings previously had made reference to claims by Regan in letters to Iraq and Libya that he had "removed 800 pages of classified material to a hidden storage area." Prosecutors also said in court documents that Regan had been observed in possession of plastic containers "large enough to contain a ream of paper" and packing tape.

When he was arrested at Dulles International Airport on Aug. 23, 2001, Regan was carrying a global positioning system device that could be used to mark precise locations of remote sites.

Rick Oborn, spokesman for the National Reconnaissance Office, said officials believe all of the documents and other items taken by Regan have been recovered. There was a sense of urgency to find all of them quickly, lest an unfriendly government begin its own digging operation.

Oborn said officials were still assessing potential intelligence damage done by Regan's activities, and whether any of the information was passed to foreign governments before it was buried. The agency itself has also done a thorough review of security procedures and its methods of screening employees, he said.

"It has caused us to take a look at how everything is done," Oborn said.